Light emitting device driver apparatus with multiple dimming modes and conversion control circuit thereof

A conversion control circuit, configured to operably control alight emitting device driver apparatus, the light emitting device driver apparatus including an inductor and a power switch which is coupled to the inductor, the power switch being configured to operably switch the inductor to convert an input power to generate an output current for driving a light emitting device circuit;

• the conversion control circuit, configured to operably control the power switch so as to control the light emitting device driver apparatus, comprising:
• a modulation circuit, configured to operably perform a pulse width modulation according to a current related signal and a reference current signal to generate a first PWM signal, wherein the modulation circuit controls the current related signal such that the current related signal corresponds to the reference current signal, wherein the current related signal relates to the output current;
• a logic driving circuit, configured to operably generate a switch control signal according to the first PWM signal and a second PWM signal to control the power switch to generate the output current;
• and
• a dimming control circuit, configured to operably generate the reference current signal according to a dimming signal,
• wherein:
• when the dimming signal exceeds a first dimming threshold, the reference current signal is generated according to a level of the dimming signal, and the switch control signal controls the power switch according to the first PWM signal, such that the output current corresponds to the level of the dimming signal, whereby an analog dimming control is performed;
• and
• when the dimming signal does not exceed the first dimming threshold, the reference current signal is clamped to a level which corresponds to the first dimming threshold, and the second PWM signal is generated according to the level of the dimming signal, wherein a frequency of the second PWM signal is lower than a frequency of the first PWM signal;
• wherein the second PWM signal enables the first PWM signal to generate the switch control signal to control the power switch, wherein, during an enable period of the second PWM signal, the output current corresponds to the first dimming threshold, and during a disable period of the second PWM signal, the power switch is controlled to be OFF, whereby a pulse width modulation dimming control is performed.